Hi Trying to install
but getting "Undefine index: id" notice with blank page

• 1
  Notice (8): Undefined index: id [APP/Model/User.php, line 152]
  Warning (2): Cannot modify header information - headers already sent by (output started at lib/Cake/Utility/Debugger.php:794) [CORE/Cake/Network/CakeResponse.php, line 449]
• 2
  what files and directories should be Writable for installation ??